Golf club set having an elastomer element for ball speed control

ABSTRACT

A set of iron-type golf club heads, each club head including a club head body including a back portion and a striking face, wherein the back portion is spaced from the striking, a elastomer element extending from the back portion to the rear surface of the striking face, and an unsupported face percentage including a percentage of the striking face area not supported by the elastomer element, wherein a loft angle of each of the plurality of golf club heads increases through the set, wherein an MOI-Y of each of the plurality of golf club heads increases through the set as the loft angle increases through the set, wherein the unsupported face percentage of each of the plurality of golf club heads decreases through the set as the loft angle increases through the set.

RELATED APPLICATIONS

The current application is a continuation-in-part of U.S. patent application Ser. No. 15/220,122, Golf Club Having an Elastomer Element for Ball Speed Control, to Morin et al. filed Jul. 26, 2016, currently pending, the disclosure of which is incorporated by reference in its entirety.

BACKGROUND

It is a goal for golfers to reduce the total number of swings needed to complete a round of golf, thus reducing their total score. To achieve that goal, it is generally desirable to for a golfer to have a ball fly a consistent distance when struck by the same golf club and, for some clubs, also to have that ball travel a long distance. For instance, when a golfer slightly mishits a golf ball, the golfer does not want the golf ball to fly a significantly different distance. At the same time, the golfer also does not want to have a significantly reduced overall distance every time the golfer strikes the ball, even when the golfer strikes the ball in the “sweet spot” of the golf club.

SUMMARY

One non-limiting embodiment of the present technology includes a set of iron-type golf club heads, including a first golf club head including a first club head body including a first back portion and a first striking face, wherein the first striking face comprises a first front surface configured to strike a golf ball and a first rear surface opposite the first front surface, wherein the first back portion is spaced from the first rear surface, a first elastomer element extending from the first back portion to the first rear surface of the first striking face, a first loft angle, a first MOI-Y, a first striking face area, and a first unsupported face percentage including a percentage of the first striking face area not supported by the first elastomer element, and a second golf club head including a second club head body including a second back portion and a second striking face, wherein the second striking face comprises a second front surface configured to strike a golf ball and a second rear surface opposite the second front surface, wherein the second back portion is spaced from the second rear surface, a second elastomer element extending from the second back portion to the second rear surface of the second striking face, a second loft angle, a second striking face area, and a second unsupported face percentage including a percentage of the second striking face area not supported by the second elastomer element, wherein the first loft angle is less than the second loft angle, wherein the first unsupported face percentage is greater than the second unsupported face percentage, wherein the first MOI-Y is lower than the second MOI-Y.

In an additional non-limiting embodiment of the present technology the first elastomer element is spaced from a first striking face perimeter and wherein the second elastomer element is spaced from a second striking face perimeter.

In an additional non-limiting embodiment of the present technology the first striking face is substantially constant in thickness and wherein the second striking face is substantially constant in thickness.

In an additional non-limiting embodiment of the present technology the first striking face is constant in thickness and wherein the second striking face is constant in thickness.

In an additional non-limiting embodiment of the present technology the first elastomer element displays an elastic modulus of about 1 to about 50 GPa and wherein the second elastomer element displays an elastic modulus of about 1 to about 50 GPa.

In an additional non-limiting embodiment of the present technology a first area of a first supported region comprises a portion of the first rear surface of the first striking face supported by the first elastomer element and wherein a second area of a second supported region comprises a portion of the second rear surface of the second striking face supported by the second elastomer element, wherein the first area of the first supported region is greater than 60 millimeters² and less than 100 millimeters² and wherein the second area of the second supported region is greater than 60 millimeters² and less than 100 millimeters².

In an additional non-limiting embodiment of the present technology the first area of the first supported region is greater than 70 millimeters² and less than 80 millimeters² and wherein the second area of the second supported region is greater than 70 millimeters² and less than 80 millimeters².

In an additional non-limiting embodiment of the present technology the first unsupported face percentage is greater than 90% and less than 99% and wherein the second unsupported face percentage is greater than 90% and less than 99%.

In an additional non-limiting embodiment of the present technology the first unsupported face percentage is greater than 95% and less than 98% and wherein the second unsupported face percentage is greater than 95% and less than 98%.

An additional non-limiting embodiment of the present technology includes a set of iron-type golf club heads, including a first golf club head including a first club head body including a first back portion and a first striking face, wherein the first striking face comprises a first front surface configured to strike a golf ball and a first rear surface opposite the first front surface, wherein the first back portion is spaced from the first rear surface, a first elastomer element extending from the first back portion to the first rear surface of the first striking face, a first loft angle, a first MOI-Y, a first striking face area, and a first unsupported face percentage including a percentage of the first striking face area not supported by the first elastomer element, and a second golf club head including a second club head body including a second back portion and a second striking face, wherein the second striking face comprises a second front surface configured to strike a golf ball and a second rear surface opposite the second front surface, wherein the second back portion is spaced from the second rear surface, a second elastomer element extending from the second back portion to the second rear surface of the second striking face, a second loft angle, a second striking face area, and a second unsupported face percentage including a percentage of the second striking face area not supported by the second elastomer element, wherein the first loft angle is greater than or equal to 20 degrees and less than or equal to 24 degrees and the second loft angle is greater than or equal to 28 degrees and less than or equal to 32 degrees, wherein the first unsupported face percentage is greater than the second unsupported face percentage, wherein the first MOI-Y is lower than the second MOI-Y.

In an additional non-limiting embodiment of the present technology the first elastomer element is spaced from a first striking face perimeter and wherein the second elastomer element is spaced from a second striking face perimeter.

In an additional non-limiting embodiment of the present technology the first striking face is substantially constant in thickness and wherein the second striking face is substantially constant in thickness.

In an additional non-limiting embodiment of the present technology the first striking face is constant in thickness and wherein the second striking face is constant in thickness.

In an additional non-limiting embodiment of the present technology the first elastomer element displays an elastic modulus of about 1 to about 50 GPa and wherein the second elastomer element displays an elastic modulus of about 1 to about 50 GPa.

In an additional non-limiting embodiment of the present technology a first area of a first supported region comprises a portion of the first rear surface of the first striking face supported by the first elastomer element and wherein a second area of a second supported region comprises a portion of the second rear surface of the second striking face supported by the second elastomer element, wherein the first area of the first supported region is greater than 60 millimeters² and less than 100 millimeters² and wherein the second area of the second supported region is greater than 60 millimeters² and less than 100 millimeters².

In an additional non-limiting embodiment of the present technology the first area of the first supported region is greater than 70 millimeters² and less than 80 millimeters² and wherein the second area of the second supported region is greater than 70 millimeters² and less than 80 millimeters².

In an additional non-limiting embodiment of the present technology the first unsupported face percentage is greater than 90% and less than 99% and wherein the second unsupported face percentage is greater than 90% and less than 99%.

In an additional non-limiting embodiment of the present technology the first unsupported face percentage is greater than 95% and less than 98% and wherein the second unsupported face percentage is greater than 95% and less than 98%.

An additional non-limiting embodiment of the present technology includes a set of iron-type golf club heads, including a plurality of golf club heads, each including a club head body including a back portion and a striking face, wherein the striking face comprises a front surface configured to strike a golf ball and a rear surface opposite the front surface, wherein the back portion is spaced from the rear surface, a elastomer element extending from the back portion to the rear surface of the striking face, and an unsupported face percentage including a percentage of the striking face area not supported by the elastomer element, wherein a loft angle of each of the plurality of golf club heads increases through the set, wherein an MOI-Y of each of the plurality of golf club heads increases through the set as the loft angle increases through the set, wherein the unsupported face percentage of each of the plurality of golf club heads decreases through the set as the loft angle increases through the set.

In an additional non-limiting embodiment of the present technology the plurality of golf club heads comprises at least three golf club heads.

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive examples are described with reference to the following Figures.

FIGS. 1A-1B depict section views of a golf club head having an elastomer element.

FIG. 1C depicts a perspective section view of the golf club head depicted in FIGS. 1A-1B.

FIGS. 2A-2B depict section views of a golf club head having an elastomer element and a striking face with a thickened center portion.

FIGS. 3A-3B depict section views of a golf club head having an elastomer element and an adjustment mechanism to adjust the compression of the elastomer element.

FIG. 4A depicts a perspective view of another example of a golf club head having an elastomer element and an adjustment mechanism to adjust the compression of the elastomer element.

FIG. 4B depicts a section view of the golf club head of FIG. 4A.

FIG. 4C depicts a section view of another example of a golf club having an elastomer element and an adjustment mechanism to adjust the compression of the elastomer element.

FIG. 5A depicts a stress contour diagram for a golf club head without an elastomer element.

FIG. 5B depicts a stress contour diagram for a golf club head with an elastomer element.

FIG. 6A depicts a front view of the golf club head.

FIG. 6B depicts a toe view of the golf club head of FIG. 6A.

FIG. 6C depicts a section view A-A of the golf club head of FIG. 6A.

FIG. 6D depicts a perspective view of the golf club head of FIG. 6A oriented perpendicular to the striking face.

FIG. 6E depicts a perspective view of the golf club head of FIG. 6A oriented perpendicular to the striking face including the supported region.

DETAILED DESCRIPTION

The technologies described herein contemplate an iron-type golf club head that incorporates an elastomer element to promote more uniform ball speed across the striking face of the golf club. Traditional thin-faced iron-type golf clubs generally produce less uniform launch velocities across the striking face due to increased compliance at the geometric center of the striking face. For example, when a golf club strikes a golf ball, the striking face of the club deflects and then springs forward, accelerating the golf ball off the striking face. While such a design may lead to large flight distances for a golf ball when struck in the center of the face, any off-center strike of golf ball causes significant losses in flight distance of the golf ball. In comparison, an extremely thick face causes more uniform ball flight regardless of impact location, but a significant loss in launch velocities. The present technology incorporates an elastomer element between a back portion of the hollow iron and the rear surface of the striking face. By including the elastomer element, the magnitude of the launch velocity may be reduced for strikes at the center of the face while improving uniformity of launch velocities across the striking face. In some examples, the compression of the elastomer element between the back portion and the striking face may also be adjustable to allow for a golfer or golf club fitting professional to alter the deflection of the striking face when striking a golf ball.

FIGS. 1A-1B depict section views depict section views of a golf club head 100 having an elastomer element 102. FIG. 1C depicts a perspective section view of the golf club head 100. FIGS. 1A-1C are described concurrently. The club head 100 includes a striking face 118 and a back portion 112. A cavity 120 is formed between the striking face 118 and the back portion 112. An elastomer element 102 is disposed in the cavity 120 between the striking face 118 and the back portion 112. A rear portion of the elastomer element 102 is held in place by a cradle 108. The cradle 108 is attached to the back portion 112 of the golf club head 100, and the cradle 108 includes a recess 109 to receive the rear portion of the elastomer element 102. The lip of the cradle 108 prevents the elastomer element 102 from sliding or otherwise moving out of position. The elastomer element 102 may have a generally frustoconical shape, as shown in FIGS. 1A-1B. In other examples, the elastomer element 102 may have a cylindrical, spherical, cuboid, or prism shape. The recess 109 of the cradle 108 is formed to substantially match the shape of the rear portion of the elastomer element 102. For example, with the frustoconical elastomer element 102, the recess 109 of the cradle 108 is also frustoconical such that the surface of the rear portion of the elastomer element 102 is in contact with the interior walls of the recess 109 of the cradle 108. The cradle 108 may be welded or otherwise attached onto the back portion 112, or the cradle 108 may be formed as part of the back portion 112 during a casting or forging process. The back portion 112 may also be machined to include the cradle 108.

A front portion 103 of the elastomer element 102 contacts the rear surface 119 of the striking face 118. The front portion 103 of the elastomer element 102 may be held in place on the rear surface 119 of the striking face 118 by a securing structure, such as flange 110. The flange 110 protrudes from the rear surface 119 of the striking face 118 into the cavity 120. The flange 110 receives the front portion 103 of the elastomer element 102 to substantially prevent the elastomer element 102 from sliding along the rear surface 119 of the striking face 118. The flange 110 may partially or completely surround the front portion 103 of the elastomer element 102. Similar to the cradle 108, the flange 110 may be shaped to match the shape of the front portion 103 of the elastomer element 102 such that the surface of the front portion 103 of the elastomer element 102 is in contact with the interior surfaces of the flange 110. The flange 110 may be welded or otherwise attached to the rear surface 119 of the striking face 118. The flange 110 may also be cast or forged during the formation of the striking face 118. For instance, where the striking face 118 is a face insert, the flange 110 may be incorporated during the casting or forging process to make the face insert. In another example, the flange 110 and the striking face 118 may be machined from a thicker face plate. Alternative securing structures other than the flange 110 may also be used. For instance, two or more posts may be included on rear surface 119 of the striking face 118 around the perimeter of the front portion 103 of the elastomer element 102. As another example, an adhesive may be used to secure the elastomer element 102 to the rear surface 119 of the striking face 118. In other embodiments, no securing structure is utilized and the elastomer element 102 is generally held in place due to the compression of the elastomer element 102 between the cradle 108 and the rear surface 119 of the striking face 118.

In the example depicted in FIGS. 1A-1C, the elastomer element 102 is disposed behind the approximate geometric center of the striking face 118. In traditional thin face golf clubs, strikes at the geometric center of the striking face 118 display the largest displacement of the striking face 118, and thus the greatest ball speeds. By disposing the elastomer 102 at the geometric center of the striking face 118, the deflection of the striking face 118 at that point is reduced, thus reducing the ball speed. Portions of the striking face 118 not backed by the elastomer element 102, however, continue to deflect into the cavity 120 contributing to the speed of the golf ball. As such, a more uniform distribution of ball speeds resulting from ball strikes across the striking face 118 from the heel to the toe may be achieved. In other examples, the elastomer element 102 may be disposed at other locations within the club head 100.

The elasticity of the elastomer element 102 also affects the deflection of the striking face 118. For instance, a material with a lower elastic modulus allows for further deflection of the striking face 118, providing for higher maximum ball speeds but less uniformity of ball speeds. In contrast, a material with a higher elastic modulus further prevents deflection of the striking face 118, providing for lower maximum ball speeds but more uniformity of ball speeds. Different types of materials are discussed in further detail below with reference to Tables 2-3.

The golf club head 100 also includes a sole 105 having a sole channel 104 in between a front sole portion 114 and a rear sole portion 116. The sole channel 104 extends along the sole 105 of the golf club head 100 from a point near the heel to a point near the toe thereof. While depicted as being a hollow channel, the sole channel 104 may be filled or spanned by a plastic, rubber, polymer, or other material to prevent debris from entering the cavity 120. The sole channel 104 allows for additional deflection of the lower portion of the striking face 118. By allowing for further deflection of the lower portion of the striking face 118, increased ball speeds are achieved from ball strikes at lower portions of the striking face 118, such as ball strikes off the turf. Accordingly, the elastomer element 102 and the sole channel 104 in combination with one another provide for increased flight distance of a golf ball for turf strikes along with more uniform ball speeds across the striking face 118.

FIGS. 2A-2B depict sections views of a golf club head 200 having an elastomer element 202 and a striking face 218 with a thickened center portion 222. Golf club head 200 is similar to golf club head 100 discussed above with reference to FIGS. 1A-1C, except a thickened portion 222 of the striking face 218 is utilized rather than a flange 110. The thickened portion 222 of the striking face 218 protrudes into the cavity 220. The front portion 203 of the elastomer element 202 contacts the rear surface 219 of the thickened portion 222. The rear portion of the elastomer element 202 is received by a recess 209 in a cradle 208, which is attached to the back portion 212 and substantially similar to the cradle 108 discussed above with reference to FIGS. 1A-1C. Due the thickened portion 222 of the striking face 218, the elastomer element 202 may be shorter in length than the elastomer element 102 in FIGS. 1A-1C. The golf club head 200 also includes a sole channel 204 disposed between a front sole portion 214 and a rear sole portion 216. The sole channel 204 also provides benefits similar to that of sole channel 104 described in FIGS. 1A-1C and may also be filled with or spanned by a material.

FIGS. 3A-3B depict section views of a golf club head 300 having an elastomer element 302 and an adjustment mechanism to adjust the compression of the elastomer element 302. The golf club head 300 includes a striking face 318 and a back portion 312, and a cavity 320 is formed between the back portion 312 and the striking face 318. Similar to the golf club head 100 described above with reference to FIGS. 1A-1C, a flange 310 is disposed on the rear surface 319 of the striking face 318, and the flange 310 receives the front portion 303 of the elastomer element 302. In the example depicted in FIGS. 3A-3B, the elastomer element 302 has a generally cylindrical shape. In other examples, however, the elastomer element 302 may have a conical, frustoconical, spherical, cuboid, or prism shape.

The golf club head 300 also includes an adjustment mechanism. The adjustment mechanism is configured to adjust the compression of the elastomer element 302 against the rear surface 319 of the striking face 318. In the embodiment depicted in FIGS. 3A-3B, the adjustment mechanism includes an adjustment receiver 306 and an adjustment driver 330. The adjustment receiver 306 may be a structure with a through-hole into the cavity 320, and the adjustment driver 330 may be a threaded element or screw, as depicted. The through-hole of the adjustment receiver 306 includes a threaded interior surface for receiving the threaded element 330. The adjustment receiver 306 may be formed as part of the forging or casting process of the back portion 312 or may also be machined and tapped following the forging and casting process. The threaded element 330 includes an interface 334, such as a recess, that contacts or receives a rear portion of the elastomer element 302. The threaded element 330 also includes a screw drive 332 that is at least partially external to the golf club head 300 such that a golfer can access the screw drive 332. When the threaded element 330 is turned via screw drive 332, such as by a screwdriver, Allen wrench, or torque wrench, the threaded element 330 moves further into or out of the cavity 320. In some examples, the interface 334 that contacts or receives the rear portion of the elastomer element 302 may be lubricated so as to prevent twisting or spinning of the elastomer element 302 when the threaded element 330 is turned. As the threaded element 330 moves further into the cavity 320, the compression of the elastomer element 302 against the rear surface 319 of the striking face 318 increases, thus altering a performance of the elastomer element 302.

A higher compression of the elastomer element 302 against the rear surface 319 of the striking face 318 further restricts the deflection of the striking face 318. In turn, further restriction of the deflection causes more uniform ball speeds across the striking face 318. However, the restriction on deflection also lowers the maximum ball speed from the center of the striking face 318. By making the compression of the elastomer element 302 adjustable with the adjustment mechanism, the golfer or a golf-club-fitting professional may adjust the compression to fit the particular needs of the golfer. For example, a golfer that desires further maximum distance, but does not need uniform ball speed across the striking face 318, can reduce the initial set compression of the elastomer element 302 by loosening the threaded element 330. In contrast, a golfer that desires uniform ball speed across the striking face 318 can tighten the threaded element 330 to increase the initial set compression of the elastomer element 302.

While the adjustment mechanism is depicted as including a threaded element 330 and a threaded through-hole in FIGS. 3A-3B, other adjustment mechanisms could be used to adjust the compression of the elastomer element 302 against the rear surface 319 of the striking face 318. For instance, the adjustment mechanism may include a lever where rotation of the lever alters the compression of the elastomer element 302. The adjustment mechanism may also include a button that may be depressed to directly increase the compression of the elastomer element 302. Other types of adjustment mechanisms may also be used.

The golf club head 300 also includes a sole channel 304 between a front sole portion 314 and a rear sole portion 316, similar to the sole channel 104 discussed above with reference to FIGS. 1A-1C. The sole channel 304 also provides benefits similar to that of sole channel 104 and may also be filled with or spanned by a material.

The golf club head 300 may also be created or sold as a kit. In the example depicted where the adjustment mechanism is a threaded element 330, such as a screw, the kit may include a plurality of threaded elements 330. Each of the threaded elements 330 may have a different weight, such that the golfer can select the desired weight. For example, one golfer may prefer an overall lighter weight for the head of an iron, while another golfer may prefer a heavier weight. The plurality of threaded elements 330 may also each have different weight distributions. For instance, different threaded elements 330 may be configured so as to distribute, as desired, the weight of each threaded element 330 along a length thereof. The plurality of threaded elements 330 may also have differing lengths. By having differing lengths, each threaded elements 330 may have a maximum compression that it can apply to the elastomer element 302. For instance, a shorter threaded elements 330 may not be able to apply as much force onto the elastomer element 302 as a longer threaded elements 330, depending on the configuration of the adjustment receiver 306. The kit may also include a torque wrench for installing the threaded elements 330 into the adjustment receiver 306. The torque wrench may include preset settings corresponding to different compression or performance levels.

FIG. 4A depicts a perspective view of another example of a golf club head 400A having an elastomer element 402 and an adjustment mechanism to adjust the compression of the elastomer element 402. FIG. 4B depicts a section view of the golf club head 400A. The golf club 400A includes striking face 418 and a back portion 412 with a cavity 420 formed there between. Like the adjustment mechanism in FIGS. 3A-3B, the adjustment mechanism in golf club head 400A includes an adjustment receiver 406 and an adjustment driver 430. In the example depicted, the adjustment receiver 406 is a structure having a threaded through-hole for accepting the adjustment driver 430, and the adjustment driver 430 is a screw. In some embodiments, the adjustment receiver 406 may be defined by a threaded through-hole through the back portion 412, without the need for any additional structure.

The tip of the screw 430 is in contact with a cradle 408A that holds a rear portion of the elastomer element 402. As the screw 430 is turned, the lateral movement of the screw 430 causes the cradle 408A to move towards or away from the striking face 418. Accordingly, in some examples, the screw 430 extends substantially orthogonal to the rear surface 419 of the striking face 418. Because the cradle 408A holds the rear portion of the elastomer element 402, movement of the cradle 408A causes a change in the compression of the elastomer element 402 against the rear surface 419 of the striking face 418. As such, the compression of the elastomer element 402 may be adjusted by turning the screw 430 via screw drive 432, similar to manipulation of the threaded element 330 in golf club head 300 depicted in FIGS. 3A-3B.

FIG. 4C depicts a section view of another example of a golf club 400C having an elastomer element 402 and an adjustment mechanism to adjust the compression of the elastomer element 402. The golf club head 400C is substantially similar to the golf club head 400A depicted in FIGS. 4A-4B, except golf club head 400C includes a larger cradle 408C having a depth D greater than a depth of a comparatively smaller cradle (e.g., the cradle 408A of FIGS. 4A-4B having a depth d). The larger cradle 408C encompasses more the elastomer element 402 than a smaller cradle. By encompassing a larger portion of the elastomer element 402, the cradle 408C further limits the deformation of the elastomer element 402 upon a strike of a golf ball by golf club head 400C. Limitation of the deformation of the elastomer element 402 also may limit the potential maximum deflection of the striking face 418, and therefore may reduce the maximum ball speed for the golf club head 400C while increasing the uniformity of speeds across the striking face 418. The larger cradle 408C does not come into contact with the rear surface 419 of the striking face 418 at maximum deflection thereof. The cradle 408C itself may be made of the same material as the back portion 412, such as a steel. The cradle 408C may also be made from a titanium, a composite, a ceramic, or a variety of other materials.

The size of the cradle 408C may be selected based on the desired ball speed properties. For instance, the cradle 408C may encompass approximately 25% or more of the volume of the elastomer element 402, as shown in FIG. 4C. In other examples, the cradle 408C may encompass between approximately 25%-50% of the volume of the elastomer element 402. In yet other examples, the cradle 408C may encompass approximately 10%-25% or less than approximately 10% of the volume of the elastomer element 402. In still other examples, the cradle 408C may encompass more than 50% of the volume of the elastomer element 402. For the portion of the elastomer element 402 encompassed by the cradle 408C, substantially the entire perimeter surface of that portion of elastomer element 402 may contact the interior surfaces of the recess 409 of the cradle 408C.

The connection between the cradle 408C and the adjustment driver 430 can also be seen more clearly in FIG. 4C. The tip of the adjustment driver 430, which may be a flat surface, contacts the rear surface 407 of the cradle 408C. Thus, as the adjustment driver 430 moves into the cavity 420, the cradle 408C and the elastomer element 402 are pushed towards the striking face 418. Conversely, as the adjustment driver 430 is backed out of the cavity 420, the cradle 408C maintains contact with the adjustment driver 430 due to the force exerted from the elastomer element 402 resulting from the compression thereof. In some embodiments, the surface of the tip of the screw 430 and/or the rear surface 407 of the cradle 408C may be lubricated so as to prevent twisting of the cradle 408C. In other examples, the tip of the adjustment driver 430 may be attached to the cradle 408C such that the cradle 408C twists with the turning of the adjustment driver 430. In such an embodiment, the elastomer element 402 may be substantially cylindrical, conical, spherical, or frustoconical, and the interior 409 of the cradle 408C may be lubricated to prevent twisting of the elastomer element 402. In another example, the rear surface 419 of the striking face 418 and/or the front surface of the elastomer element 402 in contact with the rear surface 419 of the striking face 418 may be lubricated so as to allow for spinning of the elastomer element 402 against the rear surface 419 of the striking face 418.

While the golf club heads 400A and 400C are depicted with a continuous sole 414 rather than a sole channel like the golf club head 300 of FIGS. 3A-3B, other embodiments of golf club heads 400A and 400C may include a sole channel. In addition, golf club heads 400A and 400C may also be sold as kits with a plurality of screws and/or a torque wrench, similar to the kit discussed above for golf club head 300. An additional back plate may be added to the aft portion of the golf club heads 400A and 400C, while still leaving a portion of the screw exposed for adjustment.

Simulated results of different types of golf club heads further demonstrate ball speed uniformity across the face of the golf club heads including an elastomer element. Table 1 indicates ball speed retention across the face of a golf club head for several different example golf club heads. Example 1 is a baseline hollow iron having a 2.1 mm face thickness with a sole channel. Example 2 is a hollow iron with a 2.1 mm face with a rigid rod extending from the back portion to the striking face, also including a sole channel. Example 3 is a hollow iron with a striking face having a thick center (6.1 mm) and a thin perimeter (2.1 mm), also having a sole channel. Example 4 is a golf club head having an elastomer element similar to golf club head 100 depicted in FIGS. 1A-1C. The “Center” row indicates ball speeds resulting from a strike in the center of the golf club head, the “½″ Heel” row indicates the loss of ball speed from a strike a half inch from the center of the club head towards the heel, and the “½″ Toe” row indicates the loss of ball speed from a strike a half inch from the center of the club head towards the toe. All values in Table 1 are in miles per hour (mph).

TABLE 1 Impact Example Example Example Example Location 1 2 3 4 Center 134.1 132.8 133.8 133.6 ½” Heel (drop −1.0 −0.4 −0.9 −0.7 from center) ½” Toe (drop −6.9 −6.5 −6.8 −6.7 from center)

From the results in Table 1, the golf club head with the elastomer (Example 4) displays a relatively high ball speed from the center of the face, while also providing a reduced loss of ball speed from strikes near the toe or the heel of the golf club.

In addition, as mentioned above, the type of material utilized for any of the elastomer elements discussed herein has an effect on the displacement of the striking face. For instance, an elastomer element with a greater elastic modulus will resist compression and thus deflection of the striking face, leading to lower ball speeds. For example, for a golf club head similar to golf club head 400A, Table 2 indicates ball speeds achieved from using materials with different elasticity properties. All ball speeds were the result of strikes at the center of the face.

TABLE 2 Elastic Modulus Ball Speed Material (GPa) (mph) Material A 0.41 132.2 Material B 0.58 132.2 Material C 4.14 132.0 Material D 41.4 131.0

From the results in Table 2, a selection of material for the elastomer element can be used to fine tune the performance of the golf club. Any of the materials listed in Table 2 are acceptable for use in forming an elastomer element to be used in the present technology.

The different types of materials also have effect on the ball speed retention across the striking face. For example, for a golf club head similar to golf club head 400A, Table 3 indicates ball speeds achieved across the striking face from heel to toe for the different materials used as the elastomer element. The materials referenced in Table 3 are the same materials from Table 2. All speeds in Table 3 are in mph.

TABLE 3 ½” Toe Center ½” Heel Material Impact Impact Impact No Elastomer 128.7 132.2 129.4 Element Material A 128.7 132.2 129.4 (0.41 GPa) Material C 128.7 132.0 129.3 (4.1 GPa) Material D 127.9 131.0 128.7 (41 GPa)

From the results in Table 3, materials having a higher elastic modulus provide for better ball speed retention across the striking face, but lose maximum ball speed for impacts at the center of the face. For some applications, a range of elastic moduli for the elastomer element from about 4 to about 15 GPa may be used. In other applications, a range of elastic moduli for the elastomer element from about 1 to about 40 or about 50 GPa may be used.

As mentioned above with reference to FIGS. 4A-4C, the size of the cradle may also have an impact on the ball speed. For a smaller cradle, such as cradle 408A in FIGS. 4A-4B, and an elastomer element made of a 13 GPa material, a loss of about 0.2 mph is observed for a center impact as compared to the same club with no elastomer element. For a larger cradle that is about 5 mm deeper, such as cradle 408C in FIG. 4C, and an elastomer element also made of a 13 GPa material, a loss of about 0.4 mph is observed for a center impact as compared to the same club with no elastomer element. For the same larger cradle and an elastomer element made of a 0.4 GPa material, a loss of only about 0.2 mph is observed for a center impact as compared to the same club with no elastomer element.

San Diego Plastics, Inc. of National City, Calif. offers several plastics having elastic moduli ranging from 2.6 GPa to 13 GPa that would all be acceptable for use. The plastics also have yield strengths that are also acceptable for use in the golf club heads discussed herein. Table 4 lists several materials offered by San Diego Plastics and their respective elastic modulus and yield strength values.

TABLE 4 Tecapeek 30% Tecaform Carbon ABS Acetal PVC Tecapeek Fiber Thermoplastic 2.8 2.6 2.8 3.6 13 Elastic Modulus (GPa) Thermoplastic 0.077 0.031 0.088 0.118 0.240 Compressive Yield Strength (GPa)

The inclusion of an elastomer element also provide benefits in durability for the club face by reducing stress values displayed by the striking face upon impact with a golf ball. FIG. 5A depicts a stress contour diagram for a golf club head 500A without an elastomer element, and FIG. 5B depicts a stress contour diagram for a golf club head 500B with an elastomer element. In the golf club head 500A, the von Mises stress at the center of the face 502A is about 68% of the maximum von Mises stress, which occurs at the bottom face edge 504A. Without an elastomer element, the von Mises stress levels are high and indicate that the club face may be susceptible to failure and/or early deterioration. In the golf club 500B, for an elastomer element having an elastic modulus of 0.41 GPa, the von Mises stress for the face near the edge of the elastomer element 502B is reduced by about 16% and the maximum von Mises stress occurring at the bottom face edge 504B is reduced by about 18%. These von Mises stresses are still relatively high, but are significantly reduced from those of the golf club head 500A. For a golf club head 500B with an elastomer element having an elastic modulus of about 13 GPa, the von Mises stress for the face near the edge of the elastomer element 502B is reduced by about 50% and the maximum von Mises stress occurring at the bottom face edge 504B is reduced by about 56%. Such von Mises stress values are lower and are indicative of a more durable golf club head that may be less likely to fail.

FIGS. 6A-6E depict a golf club head 600 having an elastomer element 602. FIG. 6A depicts a front view of the golf club head 600. FIG. 6B depicts a toe view of the golf club head 600 of FIG. 6A. FIG. 6C depicts a section view A-A of the golf club head 600 of FIG. 6A. FIG. 6D depicts a perspective view of the golf club head 600 of FIG. 6A oriented perpendicular to the striking face 618. FIG. 6E depicts a perspective view of the golf club head 600 of FIG. 6A oriented perpendicular to the striking face 618 including the supported region 642. The golf club head 600 includes a striking face 618 configured to strike a ball, a sole 605 located at the bottom of the golf club head 600, and a back portion 612.

As illustrated in FIGS. 6A and 6B, the golf club head 600 includes a coordinate system centered at the center of gravity (CG) of the golf club head 600. The coordinate system includes a y-axis which extends vertically, perpendicular to a ground plane when the golf club head 600 is in an address position at prescribed lie and loft α. The coordinate system includes an x-axis, perpendicular to the y-axis, parallel to the striking face 618, and extending towards the heel of the golf club head 600. The coordinate system includes a z-axis, perpendicular to the y-axis and x-axis and extending through the striking face 618. The golf club head 600 has a rotational moment of inertia about the y-axis (MOI-Y), a value which represents the golf club head's resistance to angular acceleration about the y-axis.

An elastomer element 602 is disposed between the striking face 618 and the back portion 612. The striking face 618 includes a rear surface 619. The front portion 603 of the elastomer element 602 contacts the rear surface 619 of the striking face 618. As illustrated in FIGS. 6C and 6E, the striking face 618 includes a supported region 642, the portion of the rear surface 619 supported by the elastomer element 602, which is defined as the area inside the supported region perimeter 640 defined by the outer extent of the front portion 603 of the elastomer element 602 in contact with the rear surface 619 of the striking face 618. The supported region 642 is illustrated with hatching in FIG. 6E. The supported region 642 wouldn't normally be visible from the front of the golf club head 600 but was added for illustrative purposes.

The striking face 618 includes a striking face area 652, which is defined as the area inside the striking face perimeter 650 as illustrated in FIG. 6D. As illustrated in FIG. 6C, the striking face perimeter is delineated by an upper limit 654 and a lower limit 656. The upper limit 654 is located at the intersection of the substantially flat rear surface 619 and the upper radius 655 which extends to the top line of the golf club head 600. The lower limit 656 is located at the intersection of the substantially flat rear surface 619 and the lower radius 657 which extends to the sole 605 of the golf club head 600. The striking face perimeter is similarly delineated 658 (as illustrated in FIG. 6D) at the toe of the golf club head 600 (not illustrated in cross section). The heel portion of the striking face perimeter is defined by a plane 659 extending parallel to the y-axis and the x-axis offset 1 millimeter (mm) towards the heel from the heel-most extent of the scorelines 660 formed in the striking face 618. The striking face area 652 is illustrated with hatching in FIG. 6D. The limits 654, 656 of the striking face perimeter have been projected onto the striking face 618 in FIG. 6D for ease of illustration and understanding.

A plurality of golf club heads much like golf club head 600 described herein can be included in a set, each golf club head having a different loft α. Each golf club head can also have additional varying characteristics which may include, for example, MOI-Y, Striking Face Area, Area of Supported Region, and the Unsupported Face Percentage. The Unsupported Face Percentage is calculated by dividing the Area of Supported Region by the Striking Face Area and multiplying by 100% and subtracting it from 100%. An example of one set of iron type golf club heads is included in Table 5 below. The set in Table 5 includes the following lofts: 21, 24, 27, and 30. Other sets may include a greater number of golf club heads and/or a wider range of loft α values, or a smaller number of golf club heads and/or a smaller range of loft α values. Additionally, a set may include one or more golf club heads which include an elastomer element and one or more golf club heads which do not include an elastomer element.

TABLE 5 Striking Area of Unsupported Face Supported Face Loft of Iron MOI-Y Area Region Percentage (Degrees) (kg*mm²) (mm²) (mm²) (%) 21 270 2809 74 97.37 24 272 2790 74 97.35 27 276 2777 74 97.34 30 278 2742 74 97.30

An example of an additional embodiment of set of iron type golf club heads is included in Table 6 below.

TABLE 6 Striking Area of Unsupported Face Supported Face Loft of Iron MOI-Y Area Region Percentage (Degrees) (kg* mm²) (mm²) (mm²) (%) 21 272 2897 74 97.45 24 278 2890 74 97.44 27 289 2878 74 97.43 30 294 2803 74 97.36

If all other characteristics are held constant, a larger the MOI-Y value increases the ball speed of off-center hits. For clubs with a smaller MOI-Y, the decrease in off-center ball speed can be mitigated with a greater unsupported face percentage. By supporting a smaller percentage of the face, more of the face is able to flex during impact, increasing off-center ball speed. Thus, for the inventive golf club set described in Table 5 above, the MOI-Y increases through the set as loft α increases and the unsupported face percentage decreases through the set as loft α increases. This relationship creates consistent off-center ball speeds through a set of golf clubs.

A set of golf clubs can include a first golf club head with a loft greater than or equal to 20 degrees and less than or equal to 24 degrees and a second golf club head with a loft greater than or equal to 28 degrees and less than or equal to 32 degrees. In one embodiment, the set can be configured so that the first golf club head has a larger unsupported face percentage than the second golf club head and the first golf club head has a lower MOI-Y than the second golf club head.

More particular characteristics of embodiments described herein are described below. In some embodiments, the area of the supported region can be greater than 30 millimeters². In some embodiments, the area of the supported region can be greater than 40 millimeters². In some embodiments, the area of the supported region can be greater than 60 millimeters². In some embodiments, the area of the supported region can be greater than 65 millimeters². In some embodiments, the area of the supported region can be greater than 70 millimeters². In some embodiments, the area of the supported region can be greater than 73 millimeters².

In some embodiments, the area of the supported region can be less than 140 millimeters². In some embodiments, the area of the supported region can be less than 130 millimeters². In some embodiments, the area of the supported region can be less than 120 millimeters². In some embodiments, the area of the supported region can be less than 110 millimeters². In some embodiments, the area of the supported region can be less than 100 millimeters². In some embodiments, the area of the supported region can be less than 90 millimeters². In some embodiments, the area of the supported region can be less than 85 millimeters². In some embodiments, the area of the supported region can be less than 80 millimeters². In some embodiments, the area of the supported region can be less than 75 millimeters².

In some embodiments, the unsupported face percentage is greater than 70%. In some embodiments, the unsupported face percentage is greater than 75%. In some embodiments, the unsupported face percentage is greater than 80%. In some embodiments, the unsupported face percentage is greater than 85%. In some embodiments, the unsupported face percentage is greater than 90%. In some embodiments, the unsupported face percentage is greater than 95%. In some embodiments, the unsupported face percentage is greater than 96%. In some embodiments, the unsupported face percentage is greater than 97%.

In some embodiments, the unsupported face percentage is less than 99.75%. In some embodiments, the unsupported face percentage is less than 99.50%. In some embodiments, the unsupported face percentage is less than 99.25%. In some embodiments, the unsupported face percentage is less than 99.00%. In some embodiments, the unsupported face percentage is less than 98.75%. In some embodiments, the unsupported face percentage is less than 98.50%. In some embodiments, the unsupported face percentage is less than 98.25%. In some embodiments, the unsupported face percentage is less than 98.00%. In some embodiments, the unsupported face percentage is less than 97.75%. In some embodiments, the unsupported face percentage is less than 97.50%. In some embodiments, the unsupported face percentage is less than 97.25%. In some embodiments, the unsupported face percentage is less than 97.00%.

Although specific embodiments and aspects were described herein and specific examples were provided, the scope of the invention is not limited to those specific embodiments and examples. One skilled in the art will recognize other embodiments or improvements that are within the scope and spirit of the present invention. Therefore, the specific structure, acts, or media are disclosed only as illustrative embodiments. The scope of the invention is defined by the following claims and any equivalents therein. 

1. A set of iron-type golf club heads, comprising: a first golf club head comprising: a first club head body comprising a first back portion and a first striking face; wherein said first striking face comprises a first front surface configured to strike a golf ball and a first rear surface opposite said first front surface; wherein said first back portion is spaced from said first rear surface; a first elastomer element extending from said first back portion to said first rear surface of said first striking face; a first loft angle; a first MOI-Y; a first striking face area; and a first unsupported face percentage comprising a percentage of said first striking face area not supported by said first elastomer element; and a second golf club head comprising: a second club head body comprising a second back portion and a second striking face; wherein said second striking face comprises a second front surface configured to strike a golf ball and a second rear surface opposite said second front surface; wherein said second back portion is spaced from said second rear surface; a second elastomer element extending from said second back portion to said second rear surface of said second striking face; a second loft angle; a second striking face area; and a second unsupported face percentage comprising a percentage of said second striking face area not supported by said second elastomer element; wherein said first loft angle is less than said second loft angle; wherein said first unsupported face percentage is greater than said second unsupported face percentage; wherein said first MOI-Y is lower than said second MOI-Y.
 2. The set of iron-type golf club heads of claim 1, wherein said first elastomer element is spaced from a first striking face perimeter and wherein said second elastomer element is spaced from a second striking face perimeter.
 3. The set of iron-type golf club heads of claim 1, wherein said first striking face is substantially constant in thickness and wherein said second striking face is substantially constant in thickness.
 4. The set of iron-type golf club heads of claim 1, wherein said first striking face is constant in thickness and wherein said second striking face is constant in thickness.
 5. The set of iron-type golf club heads of claim 1, wherein said first elastomer element displays an elastic modulus of about 1 to about 50 GPa and wherein said second elastomer element displays an elastic modulus of about 1 to about 50 GPa.
 6. The set of iron-type golf club heads of claim 1, wherein a first area of a first supported region comprises a portion of said first rear surface of said first striking face supported by said first elastomer element and wherein a second area of a second supported region comprises a portion of said second rear surface of said second striking face supported by said second elastomer element, wherein said first area of said first supported region is greater than 60 millimeters² and less than 100 millimeters² and wherein said second area of said second supported region is greater than 60 millimeters² and less than 100 millimeters².
 7. The set of iron-type golf club heads of claim 6, wherein said first area of said first supported region is greater than 70 millimeters² and less than 80 millimeters² and wherein said second area of said second supported region is greater than 70 millimeters² and less than 80 millimeters².
 8. The set of iron-type golf club heads of claim 1, wherein said first unsupported face percentage is greater than 90% and less than 99% and wherein said second unsupported face percentage is greater than 90% and less than 99%.
 9. The set of iron-type golf club heads of claim 8, wherein said first unsupported face percentage is greater than 95% and less than 98% and wherein said second unsupported face percentage is greater than 95% and less than 98%.
 10. A set of iron-type golf club heads, comprising: a first golf club head comprising: a first club head body comprising a first back portion and a first striking face; wherein said first striking face comprises a first front surface configured to strike a golf ball and a first rear surface opposite said first front surface; wherein said first back portion is spaced from said first rear surface; a first elastomer element extending from said first back portion to said first rear surface of said first striking face; a first loft angle; a first MOI-Y; a first striking face area; and a first unsupported face percentage comprising a percentage of said first striking face area not supported by said first elastomer element; and a second golf club head comprising: a second club head body comprising a second back portion and a second striking face; wherein said second striking face comprises a second front surface configured to strike a golf ball and a second rear surface opposite said second front surface; wherein said second back portion is spaced from said second rear surface; a second elastomer element extending from said second back portion to said second rear surface of said second striking face; a second loft angle; a second striking face area; and a second unsupported face percentage comprising a percentage of said second striking face area not supported by said second elastomer element; wherein said first loft angle is greater than or equal to 20 degrees and less than or equal to 24 degrees and said second loft angle is greater than or equal to 28 degrees and less than or equal to 32 degrees; wherein said first unsupported face percentage is greater than said second unsupported face percentage; wherein said first MOI-Y is lower than said second MOI-Y.
 11. The set of iron-type golf club heads of claim 10, wherein said first elastomer element is spaced from a first striking face perimeter and wherein said second elastomer element is spaced from a second striking face perimeter.
 12. The set of iron-type golf club heads of claim 10, wherein said first striking face is substantially constant in thickness and wherein said second striking face is substantially constant in thickness.
 13. The set of iron-type golf club heads of claim 10, wherein said first striking face is constant in thickness and wherein said second striking face is constant in thickness.
 14. The set of iron-type golf club heads of claim 10, wherein said first elastomer element displays an elastic modulus of about 1 to about 50 GPa and wherein said second elastomer element displays an elastic modulus of about 1 to about 50 GPa.
 15. The set of iron-type golf club heads of claim 10, wherein a first area of a first supported region comprises a portion of said first rear surface of said first striking face supported by said first elastomer element and wherein a second area of a second supported region comprises a portion of said second rear surface of said second striking face supported by said second elastomer element, wherein said first area of said first supported region is greater than 60 millimeters² and less than 100 millimeters² and wherein said second area of said second supported region is greater than 60 millimeters² and less than 100 millimeters².
 16. The set of iron-type golf club heads of claim 15, wherein said first area of said first supported region is greater than 70 millimeters² and less than 80 millimeters² and wherein said second area of said second supported region is greater than 70 millimeters² and less than 80 millimeters².
 17. The set of iron-type golf club heads of claim 10, wherein said first unsupported face percentage is greater than 90% and less than 99% and wherein said second unsupported face percentage is greater than 90% and less than 99%.
 18. The set of iron-type golf club heads of claim 17, wherein said first unsupported face percentage is greater than 95% and less than 98% and wherein said second unsupported face percentage is greater than 95% and less than 98%.
 19. A set of iron-type golf club heads, comprising: a plurality of golf club heads, each comprising: a club head body comprising a back portion and a striking face; wherein said striking face comprises a front surface configured to strike a golf ball and a rear surface opposite said front surface; wherein said back portion is spaced from said rear surface; a elastomer element extending from said back portion to said rear surface of said striking face; and an unsupported face percentage comprising a percentage of said striking face area not supported by said elastomer element; wherein a loft angle of each of said plurality of golf club heads increases through said set; wherein an MOI-Y of each of said plurality of golf club heads increases through said set as said loft angle increases through said set; wherein said unsupported face percentage of each of said plurality of golf club heads decreases through said set as said loft angle increases through said set.
 20. The set of iron-type golf club heads of claim 19, wherein said plurality of golf club heads comprises at least three golf club heads. 